The Reproductive and Developmental Toxicology Research Core consists of seven established/junior investigators and five affiliate investigators representing a variety of disciplines including environmental health, pediatrics, pharmacology, pathology, epidemiology, and comparative medicine. The topic of this core is defined to cover reproductive events leading to gamete formation, fertilization, pre- and post-implantation and development, postnatal development, and the overall process of aging. The specific aims of the core are: 1) nurture individual and collaborative research to understand molecular and biochemical mechanisms of reproductive and developmental toxicity; 2) foster research to identify factors affecting individual susceptibility to these adverse endpoints; 3) develop biomarkers for these toxic effects that can be used in molecular epidemiology studies; and 4) promote research on women?s and children?s health problems. These aims will continue for years 6 through 10. This Core has used and will continue to use a variety of mechanisms to reach its goals. This has included group meetings, seminar speakers, visiting scientists, pilot projects, and support for sample analyses.